Daily Rhythms of Female Self-maintenance Correlate with Predation Risk and Male Nest Attendance in a Biparental Wader

Abstract

Parents make tradeoffs between care for offspring and themselves. Such a tradeoff should be reduced in biparental species, when both parents provide parental care. However, in some biparental species, the contribution of one sex varies greatly over time or between pairs. How this variation in parental care influences self-maintenance rhythms is often unclear. In this study, we used continuous video recording to investigate the daily rhythms of sleep and feather preening in incubating females of the Northern Lapwing ( Vanellus vanellus), a wader with a highly variable male contribution to incubation. We found that the female’s sleep frequency peaked after sunrise and before sunset but was low in the middle of the day and especially during the night. In contrast, preening frequency followed a 24-h rhythm and peaked in the middle of the day. Taken together, incubating females rarely slept or preened during the night, when the predation pressure was highest. Moreover, the sleeping and preening rhythms were modulated by the male contribution to incubation. Females that were paired with more contributing males showed a stronger sleep rhythm but also a weaker preening rhythm. If more incubating males also invest more in nest guarding and deterring daylight predators, their females may afford more sleep on the nest during the day and preen more when they are off the nest. Whether the lack of sleep in females paired with less caregiving males has fitness consequences awaits future investigation.

Diel timing of nest predation changes across breeding season in a subtropical shorebird

“…Second, as the season progresses and temperatures increase, we expect the parents to reduce their alertness during the day, spending more time preening and sleeping on the nest, similarly to the northern lapwings (Brynychová et al, 2020). Also, an off-nest parent on the watch for predators may not be necessary.…”

“…For example, is there a day-night nest predation pattern around the equator and around the clock nest predation toward the poles, where it is light 24 hr a day during the breeding season? Diel timing of nest predation for a given avian species likely depends on its anti-predatory strategy (Brynychová et al, 2020;Bulla et al, 2016;Eggers et al, 2008), as well as on when its main predator species are active (DeGregorio et al, 2015;Kämmerle et al, 2020).…”

“…While nest predation is relatively well studied in general, our knowledge is biased toward the Northern hemisphere temperate and arctic regions (Bulla et al., 2019 ; Freeman et al., 2020 ; Kubelka, Šálek, et al., 2018 ; Unzeta et al., 2020 ), which hampers global comparative analyses. Moreover, regardless of the region, we know fairly little about when within a day nests are predated (Tulp et al., 2001 ; hereafter “diel timing of nest predation”; Praus & Weidinger, 2010 ; Weidinger, 2010 ; DeGregorio et al., 2015 ; Brynychová et al., 2020 ; Laidlaw et al., 2020 ), perhaps because it requires continuous nest monitoring (Pietz et al., 2012 ; Weidinger, 2006 ).…”

“…Knowing when nests of a given species or population are predated may help in interpreting various behaviors of incubating parents, such as the timing of breeding season (Morton, 1971 ), pattern of nest attendance (Bakner et al., 2019 ; Cervencl et al., 2011 ; Kasun B Ekanayake et al., 2015 ; Massaro et al., 2008 ; Skórka et al., 2012 ; Sládeček et al., 2019 ), or daily rhythms of self‐maintenance activities (Brynychová et al., 2020 ; Javůrková et al., 2011 ). Notably, given the lack of information on diel timing of nest predation, it is unclear whether there is a population‐ or species‐specific, latitudinal, or habitat‐dependent pattern in the timing of predation.…”

“…Diel timing of nest predation for a given avian species likely depends on its anti‐predatory strategy (Brynychová et al., 2020 ; Bulla et al., 2016 ; Eggers et al., 2008 ), as well as on when its main predator species are active (DeGregorio et al., 2015 ; Kämmerle et al., 2020 ). For example, corvids (Corvidae) are active and search for their prey during daylight hours (Tahajjul Taufique et al., 2016 ), but ground‐nesting northern lapwings (Vanellus vanellus) actively protect their nests by chasing away corvids (and other daylight active avian predators).…”